Modified Vaccinia virus Ankara for the vaccination of neonates

ABSTRACT

The invention concern the use of a virus for the preparation of a medicament for the vaccination or treatment of a neonatal or prenatal animal, including a human, wherein the virus is capable of infecting the cells of the neonatal or prenatal animal, including a human, but not capable of being replicated to infectious progeny virus in the neonatal or prenatal animal, including a human. The virus is preferably a Modified Vaccinia Virus Ankara. In particular, the invention concerns the vaccination of neonates against infections with viruses belonging to the same virus group than the virus used for vaccination. Moreover, the invention concerns the vaccination of neonates against antigens selected from foreign antigens and tumour antigens, wherein the tumour antigen and/or the foreign antigen are different from the antigens associated with the virus. The invention further concerns the use of viruses as defined above to increase the level of factors which activate dendritic cells or their precursor cells and/or to increase the number of dendritic cells or their precursor cells and/or to increase the production and/or cellular content of an interferon (IFN) or IL-12.

The invention concern thes use of a virus for the preparation of amedicament for the vaccination or treatment of a neonatal or prenatalanimal, including a human, wherein the virus is capable of infecting thecells of the neonatal or prenatal animal, including a human, but notcapable of being replicated to infectious progeny virus in the neonatalor prenatal animal, including a human. The virus is preferably aModified Vaccinia Virus Ankara.

In particular, the invention concerns the vaccination of neonatesagainst infections with viruses belonging to the same virus group thanthe virus used for vaccination. Moreover, the invention concerns thevaccination of neonates against antigens selected from foreign antigensand tumour antigens, wherein the tumour antigen and/or the foreignantigen are different from the antigens associated with the virus. Theinvention further concerns the use of viruses as defined above toincrease the level of factors which activate dendritic cells or theirprecursor cells and/or to increase the number of dendritic cells ortheir precursor cells and/or to increase the production and/or cellularcontent of an interferon (IFN) or IL-12.

BACKGROUND OF THE INVENTION

The natural environment of animals and human beings contains a largevariety of infectious agents such as viruses, bacteria or fungi. Many ofthese infectious agents may cause diseases in the infected hosts. Undernormal circumstances the infected host recovers from the disease inducedby the infectious agent after a certain period of time. This recovery isdue to the immune system of an animal or a human being.

The immune system is the part of the human or animal body that isresponsible for eliminating the infectious agent. The immune response isdivided into a specific and an unspecific (innate) reaction althoughboth cooperate closely. The unspecific immune response is the immediatedefence against a wide variety of foreign substances and infectiousagents. In the innate immune response against viruses, Interferon(IFN)-α and IFN-β are absolutely essential to control the initial virusreplication and to activate natural killer (NK) cells for immediatekilling of infected cells. Intracellular bacterial or parasiticpathogens induce IL-12 that up regulates IFN-γ in NK cells and/or some Tcell subsets. IFN-γ activated NK cells can now kill intracellularpathogens. Moreover, IFN-γ also activates macrophages and enables themto kill internalized pathogens.

By far the richest source of IFN-α/β on a per cell basis are dendriticcells (DC), a specialized cell population strategically distributedthroughout the body. Plasmacytoid DC or CD11c⁺ CD8⁺ DC are among thebest producers of IFN-α/β. CD8⁺DC that are infected with intracellularnon-viral pathogens are the crucial cells able to secrete IL-12essential for the early steps in immune defense.

A specific immune response can be induced against a particular foreignsubstance (antigen) after a lag phase, when the organism is challengedwith this substance for the first time. The initiation of the specificimmune response is coordinated by DC, too. There is a constant trafficof these cells from the periphery to the secondary lymphoid organs, thelymph nodes or spleen where naïve T and B cells recirculate. Antigenthat is carried by DC to these organs enables activation of naïve T- andB cells to become effector T- and B cells. For this, DC not only carrythe antigen, but the plasticity of pathogen recognition allows differentgene activation in DC and thus a pathogen adjusted priming of T cells.

The specific immune response is highly efficient and is responsible forthe fact that an individual who recovers from a specific infection isprotected against this specific infection. Thus, a second infection withthe same or a very similar infectious agent causes much milder symptomsor no symptoms at all, since there is already a “pre-existing specificimmunity” to this agent. Such immunity and the immunological memory,respectively, persists for a long time, in some cases even lifelong.Accordingly, the induction of an immunological memory can be used forvaccination, i.e. to protect an individual against infection with aspecific pathogen.

For vaccination the immune system is challenged with a vaccine whichitself is less harmful than the pathogenic agent against which an immuneresponse is to be induced. The vaccine comprises or expresses epitopesthat are found in or expressed by the agent against which thevaccination is done. The organism, thus, is immunized against the agentcontaining the epitope that is part of the vaccine.

Typical vaccines are attenuated or inactivated viruses (e.g. the polioor small poxvirus vaccines), recombinant proteins (e.g. recombinantHepatitis B virus S-protein), heat inactivated bacterial toxins(Clostridium tetani toxin) or polysaccharides of the bacterial capsulewall (Streptococcus pneumoniae.

Since infectious diseases might lead to very critical conditions innewborns and sucklings, there is an interest to vaccinate children ornewborn animals as early as possible. Examples for conditions againstwhich a vaccination is desirable are poxvirus infections, includingsmallpox. However, the attempts to successfully vaccinate newborns arehampered by the fact that the immune system of newborn mammals is notyet mature. The immune system of neonatal infants and mammalian animalsis thought to mature gradually over a certain period of time. For humansthe maturation occurs during the first year of life. This is the reasonfor the fact that the neonatal age group is left open to variousinfections during this first year (Gans et al., J. Am. Med. Assoc.(1998) 280, 527-532). More particularly, the neonatal infants haveimpaired B-cell function, deficiencies in primary antigen presentationby dendritic cells and limited T-cell proliferation (Gans et al., J. Am.Med. Assoc. (1998) 280, 527-532). Shortly after birth the levels of Tcells in the spleen are 1,000 fold lower than in adults. In order toachieve at least a weak immunization it was suggested to use eitherreplicating viruses or formulations comprising an adjuvant forimmunization. However, with replication viruses there is always the riskthat the immature immune system may become overwhelmed by virusinfection or live viral vaccines since T cells are necessary for viralclearance (Hassett et al., J. Virol. (1997) 71, 7881-7888). Since thereis a reduced production of cytokines by Th-1 helper T cells in neonates,the response by the infants is predominantly Th-2. Consequently,cytotoxic T cells are not recruited and viral clearance is not achieved.

The situation in mammalian animals is very similar to the situation inhumans, i.e. the immune system after birth is not yet mature. In newbornmice, the number of splenic CD4+T cells is 80.000 and that of CD8+Tcells 1000 fold lower than in spleens of adults. Moreover, theInterferon (IFN) producing system is immature in these mice. Therefore,neonatal mice are unable to efficiently control the expansion ofintracellular pathogens by IFN at the site of infection. In addition,the low number and possibly inadequate activation stage of immune cellsare too limited to cope with the rapidly expanding pathogens orreplicating viruses used for vaccination.

Due to the risk associated with live viral vaccines it is notrecommended to vaccinate neonatal animals, including humans, withreplicating viruses. E.g. it is recommended not to vaccinate newbornsagainst smallpox with the vaccinia virus strains that have been useduntil the eradication of smallpox, such as strains Elstee, Copenhagenand NYCBH. According to recent recommendations in the USA, babiesyounger than 12 months of age should not get the smallpox vaccinescommercialized so far.

The vaccination of neonates with formulations comprising an adjuvant hasthe disadvantage that numerous harmful substances are introduced intothe body. Thus, a vaccination in human neonates is only done inemergency cases, e.g. in case of the Hepatitis B virus infection.

In summary, it is to be noted that the immune system is not mature atbirth. Since the vaccination with replication competent viruses orformulations comprising an adjuvant have significant disadvantages,infants are not vaccinated before the age of 2 months in Germany(Empfehlung der Ständigen Impfkommission STICO, 2001) or 6 weeks in theUSA (ACIP “Recommended Childhood Immunization Schedule, United States”).

The delay in the development of the immune system is compensated in partby the transfer of maternal antibodies from the mother to the sucklingduring pregnancy or by breastfeeding. However, not all infants arebreasffeed due to various reasons. Thus, there is a very critical periodof time of about 6-8 weeks in humans during which the infant having animmature and thus a not fully functional immune system does not receivematernal antibodies and during which a vaccination is usually notsuccessful or too dangerous.

The situation is very similar in mammalian animals, in particular foreconomically important animals such as cows or companion animals such ascats and dogs. To reduce costs the amount of milk the calf receives fromthe mother is often drastically reduced. Instead the calf receives amixture of milk powder, starter and specific concentrated feed,sometimes already in the first week after birth. Consequently, the calfdoes not receive the necessary amount and variety of maternal antibodiesso that the immature immune system is very susceptible to infections.Furthermore, farmers who breed calves and those who raise them for meatproduction are often not the same. At 4 to 6 weeks of age calves fromdifferent breeder farms are pooled and shipped to other farms for meatproduction. At this time maternal antibodies are low and the immunesystem is not fully developed but the animals are exposed to newinfectious agents under stress conditions. This increases the risk forinfections that could be prevented by vaccination. A similar situationcan be found in catteries or dog breeding facilities where theinfectious pressure is high.

OBJECT OF THE INVENTION

It is the object of the present invention to provide means to vaccinatenewborn humans and animals, respectively, against foreign antigens andantigens that are associated with diseases in humans and animals,respectively. More particularly, it is the object of the presentinvention to provide means allowing the accelerated maturation of theimmune system of newborn animals and humans. It is a further object ofthe present invention to provide means that allow vaccinating neonatalanimals, including humans, against poxvirus infections, in particularagainst smallpox.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention it was unexpectedly found that it ispossible to safely and efficiently vaccinate and/or treat neonatal orprenatal animals, including humans, with viruses that are capable ofinfecting cells of the neonatal or prenatal animal, including a human,but not capable of being replicated in said cells to infectious progenyvirus. In particular it has been shown that the viruses used accordingto the present invention, such as MVA, in particular MVA-BN and itsderivatives (see below), can be administered to newborns without showingany harmful effects. The vaccination of the animal with the virus leadsto a specific immune response against the virus used for vaccinationand/or to a general vaccination against foreign antigens and tumourantigens as explained below in more detail. Moreover, the viruses usedaccording to the present invention lead to an induction and/orenhancement of the maturation of the immune system, which is associatedwith an increase in the number of dendritic cells and factors such asInterferons. The vaccination with the viruses used according to thepresent invention is possible even if the formulation that isadministered to the animal does not comprise an adjuvant.

In summary, the viruses that are used according to the present invention(i) elicit an effective immune response in neonates, (ii) can beadministered without the need of an adjuvant and (iii) do not bear therisk of overwhelming the organism.

According to the present invention the protective effect is exerted forat least 5 days, preferably for at least 7, 14 or 28 days after thefirst vaccination.

Viruses that are “capable of infecting cells” are viruses harbouring onthe viral surface structures capable of interacting with the host cellsto such an extent that the virus or at least the viral genome becomesincorporated into the host cell. Although the viruses used according tothe present invention are capable of infecting the host cell, they arenot capable of being replicated to infectious progeny virus in theinfected cells. In the context of the present invention the term “virusnot capable of being replicated to infectious progeny virus in saidcells” refers to viruses the genome of which is at least partiallytranscribed and translated into viral proteins or even replicated,however, not packaged into infectious viral particles. Thus, the virusesused according to the present invention are viruses leading to abortiveinfections in the host. Abortive infections may occur for two reasons:according to the first alternative a cell may be susceptible toinfection but it may be nonpermissive for multiplication of the virus,e.g. due to the fact that not all necessary viral genes formultiplication of the virus in said cell are expressed and/or present inthe viral genome. An example for this type of virus according to thepresent invention in human cells is Modified Vaccinia Virus Ankara(MVA), which is explained in more detail below. According to the secondalternative an abortive infection may also result from infection ofcells with defective viruses, which lack a full complement of viralgenes. An example for such a virus according to the present inventionfor human cells is DISC-HSV1 (disabled single-cycle Herpes simplexvirus), i.e. a Herpes simplex virus, which is restricted to a singlecycle of infection (Dilloo et al., Blood 1997, 89: 119-127). This viruslacks the gene for the essential glycoprotein H (gH), but can be grownto high titer in a complementing cell line expressing gH. Innoncomplementing cell lines that are permissive for herpesvirus growth,it is restricted to a single cycle of replication, leading to therelease of noninfectious virus. The term “not capable of beingreplicated” refers preferably to viruses that do not replicate at all inthe cells of the vaccinated animal. However, also those viruses arewithin the scope of the present application that show a minor residualreplication activity that is controlled by the immature immune system ofthe neonate.

The virus according to the present invention may be any virus that iscapable of infecting cells of the animal but not capable of beingreplicated to infectious progeny virus in said cells. It is to beunderstood, that a virus that is capable of infecting cells of a firstanimal species but not capable of being replicated to infectious progenyvirus in said cells may behave differently in a second animal species.E.g., for humans MVA-BN and its derivatives (see below) are viruses thatare capable of infecting cells of the human but that are not capable ofbeing replicated to infectious progeny virus in human cells. The sameviruses are very efficiently replicated in chickens, i.e. in chickenMVA-BN is not a virus that is capable of infecting cells of the chickenbut not capable of being replicated to infectious progeny virus in saidcells. It is known to the person skilled in the art which virus has tobe chosen for a specific animal species. A test that allows to determinewhether a virus is capable or not capable of being replicated in aneonatal or prenatal animal is disclosed in WO 02/42480 and uses theAGR129 mice strain. The results obtained in this mice model areindicative for humans. Thus, the term “not capable of being replicatedto infectious progeny virus” as used in the present applicationcorresponds to the term “failure to replicate in vivo” as used for micein WO 02/42480. More details on this test are given below. The virusesaccording to the present invention are preferably capable of beingreplicated in at least one type of cells of at least one animal species.Thus, it is possible to amplify the virus prior to administration to theanimal that is to be vaccinated and/or treated. By way of examplereference is made to MVA-BN that can be amplified in CEF cells but thatis a virus that is not capable of being replicated to infectious progenyvirus in the neonatal or prenatal human. In this context it is to benoted that chemically or physically inactivated viruses do not have allthe properties of this preferred embodiment since inactivated virusesare capable of infecting the cells of the neonatal or prenatal animal,including a human and not capable of being replicated to infectiousprogeny virus in the neonatal or prenatal animal, including a human, butthese viruses are not capable of replicating in at least one type ofcells of at least one animal species.

Preferably the virus is a DNA virus. More preferably, for mammaliancells, in particular for human cells, the DNA virus is selected fromDISC-Hepesviruses and Modified Vaccinia virus Ankara (MVA).

Modified Vaccinia Ankara (MVA) virus is related to Vaccinia virus, amember of the genera Orthopoxvirus in the family of Poxviridae. MVA hasbeen generated by 516 serial passages on chicken embryo fibroblasts ofthe Ankara strain of vaccinia virus (CVA) (for review see Mayr, A., etaL Infection 3, 6-14 [1975]). As a consequence of these long-termpassages the resulting MVA virus deleted about 31 kilobases of itsgenomic sequence and, therefore, was described as highly host cellrestricted to avian cells (Meyer, H. et al., J. Gen. Virol. 72,1031-1038 [1991]). It was shown, in a variety of animal models that theresulting MVA was significantly avirulent (Mayr, A. & Danner, K. [1978]Dev. Biol. Stand. 41: 225-34). Additionally, this MVA strain has beentested in clinical trials as vaccine to immunize against the humansmallpox disease (Mayr et al., Zbl. Bakt. Hyg. I, Abt. Org. B 167,375-390 [1987], Stickl etal., Dtsch. med. Wschr. 99, 2386-2392 [1974]).These studies involved over 120,000 humans, including high riskpatients, and proved that, compared to Vaccinia based vaccines, MVA haddiminished virulence or infectiousness while it maintained goodimmunogenicity.

Preferred strains according to the present invention are MVA 575,deposited at the European Collection of Animal Cell Cultures (ECACC)with the deposition number V00120707 and MVA-BN, deposited at the sameinstitution with the deposition number V000083008, and derivativesthereof, in particular if it is intended to vaccinate/treat humans. Mostpreferred for humans is MVA-BN and its derivatives.

The properties of particularly preferred MVA strains, preferably themost preferred strains for humans, such as MVA-BN and its derivatives,can be summarized as follows:

(i) capability of reproductive replication in chicken embryo fibroblasts(CEF) and in the cell line BHK, but no capability of reproductivereplication in the human cell line HaCaT,

(ii) failure to replicate in vivo,

(iii) induction of a higher immunogenicity compared to the known strainMVA 575 (ECACC V00120707) in a lethal challenge model and/or

(iv) induction of at least substantially the same level of immunity invaccinia virus prime/vaccinia virus boost regimes when compared toDNA-prime/vaccinia virus boost regimes.

The preferred MVA strains according to the present invention have theproperty (ii) failure to replicate in the organism, which is to bevaccinated or treated and/or in the corresponding test system asexplained below and preferably one additional of the above properties,more preferably two additional of the above properties. Most preferredare MVA strains having all of the above properties. An example for anMVA strain having all of the above properties in humans is MVA-BN.Preferred derivatives of MVA-BN are derivatives having in addition tofeature (ii) at least one of the above properties, more preferably atleast two of the above properties. Most preferred are MVA-BN derivativeshaving all of the above properties.

For detailed information regarding to the assays used to determinewhether a MVA strain has one or more of the above features (i) to (iv)reference is made to WO 02/42480. This publication also discloses howviruses having the desired properties can be obtained. In particular, WO02/42480 provides a detailed definition of the features of MVA-BN and ofa derivative of MVA-BN and discloses in detail the biological assaysthat are used to determine whether an MVA strain is MVA-BN or aderivative thereof. In other words, the features of MVA-BN, thedescription of biological assays allowing to evaluate whether a MVAstrain is MVA-BN or a derivative thereof and methods allowing to obtainMVA-BN or a derivative thereof are disclosed in WO 02/42480. In thefollowing it is shortly summarized how a person skilled in the artarrives in MVA strains having one or more of the above features and howhe can test whether a given MVA strain has one or more of said featuresand is thus a most preferred virus according to the present invention.The following summary is not to be understood as to limit the relevanceof WO 02/42480 for the present application to the following information.Instead, WO 02/42480 is herewith incorporated in its entirety byreference.

The term “not capable of reproductive replication” in the cell lineHaCaT (Boukamp et al. 1988, J Cell Biol 106(3): 761-71) is used in thepresent application as defined in WO 02/42480. Thus, a virus that is“not capable of reproductive replication” in the cell line HaCaT is avirus that shows an amplification ratio of less than 1 in the human cellline HaCaT. Preferably, the amplification rate of the virus used as avector according to the invention is 0.8 or less in the human cell lineHaCaT. The “amplification ratio” of a virus is the ratio of virusproduced from an infected cell (Output) to the amount originally used toinfect the cells in the first place (Input) (“amplification ratio”). Aratio of “1” between Output and Input defines an amplification statuswherein the amount of virus produced from the infected cells is the sameas the amount initially used to infect the cells. The term “derivatives”of the viruses as deposited under ECACC V00083008 refers preferably toviruses showing essentially the same replication characteristics as thedeposited strain but showing differences in one or more parts of itsgenome. Viruses having the same “replication characteristics” than thedeposited virus are viruses that replicate with similar amplificationratios than the deposited strain in CEF cells and the cell lines BHK,HeLa, HaCaT and 143B and that show a similar replication in vivo asdetermined in the AGR129 transgenic mouse model (see below).

The term “failure to replicate in vivo” is used in the presentapplication as defined in WO 02/42480. Thus, said term refers to virusesthat do not replicate in humans and in the mice model as explained in WO02/42480. The mice used in WO 02/42480 are incapable of producing matureB- and T-cells (AGR 129 mice). In particular MVA-BN and its derivativesdo not kill AGR129 mice within a time period of at least 45 days, morepreferably within at least 60 days, most preferably within 90 days afterthe infection of the mice with 10⁷ pfu virus administered intraperitonealy. Preferably, the viruses that show “failure to replicate invivo” are further characterized in that no virus can be recovered fromorgans or tissues of the AGR129 mice 45 days, preferably 60 days andmost preferably 90 days after the infection of the mice with 10⁷ pfuvirus administered intra peritonealy. Instead of the AGR129 mice anyother mouse strain can be used that is incapable of producing mature Band T cells and as such is severely immune compromised and highlysusceptible to a replicating virus.

The details of the lethal challenge experiment used to determine whethera MVA strain has “a higher immunogenicity compared to the known strainMVA 575” are explained in WO 02/42480. In such a lethal challenge modelunvaccinated mice die after the infection with replication competentvaccinia strains such as the Western Reserve strain L929 TK+or IHD-J.The infection with replication competent vaccinia viruses is referred toas “challenge” in the context of description of the lethal challengemodel. Four days after the challenge the mice are usually killed and theviral titer in the ovaries is determined by standard plaque assays usingVERO cells. The viral titer is determined for unvaccinated mice and formice vaccinated with MVA-BN and its derivatives. More specificallyMVA-BN and its derivatives are characterized in that in this test afterthe vaccination with 10² TCID₅₀/ml virus the ovary virus titers arereduced by at least 70%, preferably by at least 80%, more preferably byat least 90% compared to unvaccinated mice.

In a preferred embodiment the viruses according to the presentinvention, such as MVA, in particular MVA-BN and its derivatives, areuseful for prime/boost administration. The viruses, in particular MVAstrains that are most preferably used in the present invention, such asMVA-BN and its derivatives as well as corresponding recombinant virusesharbouring heterologous sequences, can be used to efficiently firstprime and then boost immune responses in native animals as well as inanimals with a pre-existing immunity to poxviruses. Thus the mostpreferred virus according to the present invention induces at leastsubstantially the same level of immunity in vaccinia virusprime/vaccinia virus boost regimes compared to DNA-prime/vaccinia virusboost regimes.

A vaccinia virus, in particular an MVA strain is regarded as inducing atleast substantially the same level of immunity in vaccinia virusprime/vaccinia virus boost regimes when compared to DNA-prime/vacciniavirus boost regimes if the CTL response as measured in one of the “assay1” and “assay 2” as disclosed in WO 02/42480, preferably in both assays,is at least substantially the same in vaccinia virus prime/vacciniavirus boost regimes when compared to DNA-prime/vaccinia virus boostregimes. More preferably the CTL response after vaccinia virusprime/vaccinia virus boost administration is higher in at least one ofthe assays, when compared to DNA-prime/vaccinia virus boost regimes.Most preferably the CTL response is higher in both assays.

The virus used according to the present invention may be anon-recombinant virus, such as MVA, i.e. a virus that does not containheterologous nucleotide sequences. An example for a non-recombinantvaccinia virus is MVA-BN and its derivatives. Alternatively the virusmay be a recombinant virus, such as a recombinant MVA that containsadditional nucleotide sequences, which are heterologous to the virus.

The term “heterologous” as used in the present application refers to anycombination of nucleic acid sequences that is not normally foundintimately associated with the virus in nature, such virus is alsocalled “recombinant virus”.

The heterologous nucleic acid sequence is preferably selected from asequence coding for at least one antigen, antigenic epitope, beneficialproteins and/or therapeutic compound.

The term “beneficial proteins” as used in the present application refersto any proteins that are helpful in protecting an animal against anantigen selected from tumour antigen and foreign antigen, wherein thetumour antigen and the foreign antigen is different from the antigensassociated with the virus. Alternatively and more particulary the“beneficial proteins” are active in increasing the level of factorswhich activate dendritic cells and/or active in increasing the number ofdendritic cells and/or active in increasing the production and/orcellular content of an interferon (IFN) or IL-12. Thus, examples forsuch beneficial proteins are interferons such as IFN-alpha or IFN-beta,IL-12, Flt-3-L and or GM-CSF.

The antigenic epitopes may be any epitopes to which it makes sense toinduce an immune response. Examples for antigenic epitopes are epitopesfrom Plasmodium falciparum, Mycobacteria, Influenza virus, from virusesselected of the family of Flaviviruses, Paramyxoviruses, Hepatitisviruses, Human immunodeficiency viruses or from viruses causinghemorrhagic fever such as Hantaviruses or Filoviruses, i.e., Ebola orMarburg virus. Thus, if e.g. a recombinant MVA expressing heterologousepitopes is used to vaccinate neonates according to the presentinvention, the result of this treatment is not only a generalvaccination due to the accelerated maturation of the immune system butalso a specific vaccination against the heterologous epitope expressedfrom the heterologous MVA.

A “therapeutic compound” encoded by the heterologous nucleic acid in therecombinant virus can be, e.g., a therapeutic nucleic acid such as anantisense nucleic acid or a peptide or protein with desired biologicalactivity.

The insertion of heterologous nucleic acid sequence is preferably into anon-essential region of the virus genome. Alternatively, theheterologous nucleic acid sequence is inserted at a naturally occurringdeletion site of the viral genome (for MVA disclosed in PCT/EP96/02926).Methods how to insert heterologous sequences into the viral genome suchas a poxviral genome are known to a person skilled in the art.

The present invention also provides a pharmaceutical composition and avaccine comprising a virus according to the present invention, such asMVA, e.g., for inducing an immune response in a living animal body,including a human.

The pharmaceutical composition may generally include one or morepharmaceutical acceptable and/or approved carriers, additives,antibiotics, preservatives, adjuvants, diluents and/or stabilizers. Suchauxiliary substances can be water, saline, glycerol, ethanol, wetting oremulsifying agents, pH buffering substances, or the like. Suitablecarriers are typically large, slowly metabolized molecules such asproteins, polysaccharides, polylactic acids, polyglycollic acids,polymeric amino acids, amino acid copolymers, lipid aggregates, or thelike.

For the preparation of vaccines, the virus or its recombinants isconverted into a physiologically acceptable form. Such methods are knownto the person skilled in the art. For MVA and other poxviruses thevaccine can be prepared based on the experience in the preparation ofpoxvirus vaccines used for vaccination against smallpox (as described byStickl, H. et aL [1974] Dtsch. med. Wschr. 99, 2386-2392). For example,the purified virus is stored at −80° C. with a titre of 5×10⁸ TCID₅₀/mlformulated in about 10 mM Tris, 140 mM NaCl pH 7.4. For the preparationof vaccine shots, e.g., 10¹-10⁸ particles of the virus such as MVA arelyophilized in 100 ml of phosphate-buffered saline (PBS) in the presenceof 2% peptone and 1% human albumin in an ampoule, preferably a glassampoule. Alternatively, the vaccine shots can be produced by stepwisefreeze-drying of the virus in a formulation. This formulation cancontain additional additives such as mannitol, dextran, sugar, glycine,lactose or polyvinylpyrrolidone or other additives such as antioxidantsor inert gas, stabilizers or recombinant proteins (e.g. human serumalbumin) suitable for in vivo administration. The glass ampoule is thensealed and can be stored between 4° C. and room temperature for severalmonths. However, as long as no need exists the ampoule is storedpreferably at temperatures below −20° C.

For vaccination or therapy the lyophilisate can be dissolved in 0.1 to0.5 ml of an aqueous solution, preferably physiological saline or Trisbuffer, and administered either systemically or locally, i.e. byparenterally, intramuscularly or any other path of administration knowto the skilled practitioner. The mode of administration, the dose andthe number of administrations can be optimized by those skilled in theart in a known manner.

The virus according to the present invention, in particular MVA can beadministered by oral, nasal, intramuscular, intravenous,intraperitoneal, intradermal, intra-utero and/or subcutanousapplication. In small animals the inoculation for immunization ispreferably performed parenterally or nasaly, whereas in larger animalsor humans a subcutaneous, intramuscular or oral inoculation ispreferred.

MVA is administered preferably in a dose of 10¹ TCID₅₀ (tissue cultureinfectious dose) to 10⁹ TCID₅₀.

As pointed out above the virus according to the present invention, inparticular MVA, such as MVA-BN and its derivatives may be administeredin a therapeutically effective amount in a first inoculation (“priminginoculation”) and in a second inoculation (“boosting inoculation”).

In the context of the present invention the term “animal” covers alsohuman beings. More generally, the animal is a vertebrate animal,preferably a mammalian animal including a human. Specific examples foranimals are pets such as dogs, cats, economically important animals suchas calves, cattle, sheep, goats, horses, pigs and other animal such asmice, rats. For these animal species and for humans MVA and DISC-HSV areparticularly preferred viruses. The invention may also be used foreconomically important birds such as turkeys, ducks, goose and hens ifviruses are used that are capable to infect the bird's cells but notcapable of being replicated to infectious progeny virus in said cells.

The term “domestic animals” as used in the present description referspreferably to mammalian domestic animals, more preferably to dogs, cats,calves, cattle, sheep, goat, pigs, horses, deer.

According to a first alternative the viruses according to the presentinvention, in particular MVA-BN and its derivatives may be used asspecific vaccines, i.e. to elicit an immune response that protects thevaccinated newborn against diseases caused by a virulent virus belongingto the same virus group, family or genus than the virus that was usedfor vaccination. By way of example MVA as defined above, in particularMVA-BN and its derivatives can be used to vaccinate newborn humansagainst poxvirus infections, in particular against smallpox. MVA, inparticular MVA-BN and its derivatives, may also be used to vaccinatevertebrate animals against poxvirus infections of veterinary importance.According to this first alternative the virus used for vaccination maybe a non-recombinant virus, such as MVA-BN or its derivatives, or arecombinant virus harboring genes in the viral genome that are notnaturally found in said genome. Preferably, the recombinant virusharbors additional genes that are helpful in stimulating the immuneresponse. Examples for this kind of genes are cytokine genes andinterferon genes.

According to a second but related alternative neonates are vaccinatedwith a recombinant virus harboring a heterologous nucleic acid sequenceas defined above to induce an immune response against the amino acidsequence expressed from the heterologous nucleic acid sequence. By wayof example the nucleic acid sequence may code for an antigen or anantigenic epitope as defined above. Examples for a recombinant virusaccording to this embodiment are recombinant MVA, in particularrecombinant MVA-BN or a derivative thereof, comprising a heterologousnucleic acid coding for antigens from (i) viruses other than MVA, suchas HIV-1, HIV-2, Denguevirus, West-Nile Virus, Japanese Encephalitisvirus, measles virus, (ii) tumour antigens, (iii) bacteria, (iv) fungi.If the antigen expressed from the recombinant virus is e.g. an HIVantigen it is possible to use the recombinant virus to induce an immuneresponse in the vaccinated neonate against HIV and to prevent AIDS. In abroader sense the recombinant virus expressing the antigen or antigenicepitope is used to induce an immune response against the agent fromwhich the heterologous sequence is derived and/or against the agent thatcomprises the antigen or antigenic epitope.

According to a third alternative it has been unexpectedly found thatviruses that are capable of infecting the cells of the neonatal orprenatal animal, including a human, but not capable of being replicatedto infectious progeny virus in the neonatal or prenatal animal,including a human can be used for the preparation of a medicament forprotecting an animal, in particular a newborn animal, including a human,against an antigen selected from tumour antigen and foreign antigen,wherein the tumour antigen and/or the foreign antigen are different fromthe antigens associated with the virus.

According to this third alternative newborns vaccinated with the virusesaccording to the present invention, in particular with MVA, such asMVA-BN and its derivatives, are protected against a challenge withforeign antigens such as infectious agents. Thus, the viruses accordingto the present invention, in particular MVA are a general vaccine fornewborns, i.e. by vaccinating newborns with the viruses according to thepresent invention, in particular MVA the immune system of the newbornsbecomes more competent to deal with foreign antigens such as viruses. Inthe example section this is exemplified for vaccination with MVA and asubsequent challenge with Herpes simplex virus type 1. Thus, if thevirus according to the present invention, in particular MVA is used forthe vaccination of newborns the vaccinated animals are more protectedagainst foreign antigens than unvaccinated animals in the critical timespan until a functional and mature immune system is established.

According to the present invention “the tumour antigen and/or theforeign antigen is different from the antigens associated with virus”.This term is to be interpreted in that according to this embodiment theinvention is not primarily intended to use a virus such as MVA to inducean immune response against the virus itself. Instead the virus is usedto induce a immune response or at least a general immune stimulationthat protects the host against foreign antigens and tumour antigens,respectively, that are not associated with the virus. The term “antigensassociated with the virus” refers to epitopes and antigens of the virusparticle and to antigens and epitopes on the surface of a cell infectedwith the virus that are the result of the expression of the viralgenome.

In the context of this embodiment the term “foreign antigens” refers toany antigens and epitopes that are not naturally a part or a componentof the animal body. Foreign antigens are especially antigens andepitopes from infectious agents and toxins, Typical infectious agentsare viruses such as herpesviruses, retroviruses, rabiesviruses,rhabdoviruses, adenoviruses; bacteria such as Salmonella, Mycoplasm,Meningicoccus, Hemophilus; prions or fungi.

The invention is not only of interest to vaccinate animals againstforeign antigens but, in an alternative embodiment, is also suitable tovaccinate against tumour antigens. “Tumour antigens” are antigensassociated with certain tumoural diseases. Tumour antigens are mostoften antigens encoded by the genome of the host that develops thetumour. Thus, in a strict sense tumour antigens are not foreignantigens. However, tumour antigens are found in significant amounts intumours, whereas the amount of tumour antigens in normal tissues issignificantly lower and most often no tumour antigens are found at allin normal tissue. Examples for tumour antigens are known to the personskilled in the art and include e.g. the MAGE antigens. MVA is effectiveagainst these tumour antigens since the vaccination of animals leads toan activation and/or accelerated maturation of the immune system whichthen may lead to the destruction of tumour cells.

The term “protecting against an antigen” refers to the development of animmune response, which is directed against the foreign or tumourantigen. If the foreign antigen is an infectious agent the host isprotected against said agent, i.e. the host develops an immune responseagainst said antigen. Consequently, the infection with the infectiousagent leads to a less severe disease or to no disease at all. The term“protecting” is not to be understood in the sense that there is always a100% protection against the foreign or tumour antigen. Instead, the term“protection” as used in the present application refers to any beneficialeffect that helps the animal to deal with the foreign antigen and thetumour antigen, respectively.

According to the present invention such a protective effect is exertedfor at least 5 days, preferably for at least 7, 14 or 28 days after thefirst vaccination. In other words, the vaccinated and or treated animalis protected e.g. against a foreign antigen if the animal comes intocontact with said antigen after 5, 7, 14 and 28 days, respectively.

In the context of the present invention the effect of the vaccination ofnewborns with the virus according to the present invention, inparticular with MVA may be explained by the induction or enhancement ofmaturation of the immune system and/or the activation of the immunesystem. In the context of the present invention the term “induction orenhancement of the the maturation of the immune system” refers interalia to the accelerated increase of dendritic cells or their precursorsin vaccinees relative to controls. The terms “acceleration of thematuration” of the immune system an “enhancement of the maturation” ofthe immune system are used interchangeably in this description.

The “activation of the immune system” is characterized by the expressionon the surface of cells of molecules and hormones that ease cell/cellinteraction or trafficking and/or by the secretion of said molecules andhormones by the cells. Specific receptors take up these signals andrespond. Activation markers are inter alia Flt3-L, IL-12, IFN-alpha,MHC-II and CD8, in particular CD8alpha (see below).

The accelerated development/maturation of the immune system iscorrelated with an increase of the level of factors activating and ormobilizing dendritic cells (DC) or their precursor cells and/or anincrease in the number of dendritic cells and their precursor cellsand/or an increase in the production and/or cellular content of aninterferon or IL-12. An example for DC precursor cells that are inducedby the virus according to the present invention, in particular by MVA,are plasmacytoid DC precursors that are very important for the defenceagainst viral infections and that seem to produce IFN α/β.

More specifically, the enhancement of the maturation of the immunesystem is preferably defined by an at least 2-fold increase in surfacemarkers found on DC, such as MHC-II, CD40 and/or CD80/86. Preferablysuch an increase may be measured in the blood. Further markers tocharacterize an enhancement of the maturation of the immune system areFlt3-L, IL-12, IFN-alpha, MHC-II and CD8a (see below). Moreover, theaccelerated maturation of the immune system is preferably correlated toan at least 1.5 fold increase, preferably an at least 2.0 fold increasein the number of CD11c positive cells in the blood and/or the spleen 7days after the administration of MVA-BN to newborn animals compared tocontrol animals that have not received MVA-BN. Moreover, the enhancementof maturation of the immune system may preferably be correlated with anat least 1.5 fold increase, more preferably an at least 2.0 foldincrease of the concentration of Flt3-L two days after the vaccinationof neonates with viruses according to the present invention, whencompared to age matched controls.

In this context it is to be noted that there is an association betweenthe phenotype and function of murine and human DC populations that canbe characterised by their surface phenotype (Hochrein et al. 2002. Hum.Immunol. 63: 1103). DC in the blood can be detected using flow cytometryusing a range of surface markers (MacDonald et al. 2002. Blood.100:4512) that also allow specific populations of DC, such as theplasmactoid DC to be identified (Dzionek et al. 2002. Hum Immunol. 63:1133; Dzionek et al 2000. J. Immunol. 165: 6037). Using similartechniques DC can also be detected in other human tissues (Summers etal. 2001. Am. J. Pathol. 159: 285).

According to the present invention the viruses as defined above mightalso be used to treat neonatal or prenatal animals to increase the levelof factors activating and or mobilizing dendritic cells (DC) or theirprecursor cells and/or an increase in the number of dendritic cells andtheir precursor cells and/or an increase in the production and/orcellular content of an interferon or IL-1 2. It has been demonstratedthat following vaccination with MVA-BN the plasmacytoid dendritic cellsmake significantly more IL-12 and have an increased IFN-alpha productionand upregulation of MHC-II and CD8a. The increase of IL-12 after theadministration of the viruses used according to the present invention ispreferably 2 times, more preferably 100 times, 500 times, 1000 times,2500 times or 5000 times. The increase of the concentration of FIt3-Ltwo days after the vaccination of neonates with viruses according to thepresent invention, most preferably with MVA-BN or its derivatives, ispreferably 1.5 fold, more preferably 2.0 fold when compared to agematched controls.

The term “activation of dendritic cells or their precursors” refers tothe maturation of DC to antigen presenting cells through ill-definedcell stages driven by hormones and stimuli. The intermediates of DC aretermed precursors. These immature DC reach the periphery. Different(antigenic) stimuli activate DC. Activation markers, which areupregulated in activated dendritic cells are inter alia Flt3-L, IL-12,IFN-alpha, MHC-II and CD8a (see below).

It was noted that hormones such GM-CSF lead to more immature DC in theperiphery. Because GM-CSF leads to more DC precursor in bone marrow,blood and peripheral organs (and the cells have to move there), thisphenomenon has been termed “mobilization of dendritic cells or theirprecursors”. This definition is also used in the present description.

Consequently, the vaccination of animals including a human is especiallyuseful, if it is intended to increase the level of factors activatingdendritic cells (DC) or their precursor cells and/or to increase thenumber of dendritic cells or their precursor cells and/or to increasethe production and/or cellular content of an interferon or IL-12.

Factors that activate dendritic cells comprise inter alia Flt3-L (Lymanet al., Cell 1993, 75: 1157-1167) and GM-CSF. Typical interferonsaccording to the present invention are IFN-alpha and IFN-beta. Theviruses used according to the present invention induce Flt3-L and it isassumed that some of the beneficial effects observed are due to saidinduction.

In the context of the present application a newborn animal or human isdefined as a animal or human not yet having a mature immune system.Throughout this specification the terms “newborn animal” and “neonatalanimal” are used synonymously. A mature immune system is characterizedby the ability to fully activate the innate immune system and by thefact that all known T and B cell functions and products are in place, inparticular immunoglobulin isotypes such as IgA and IgE. Thus an immatureimmune system is characterized by a low number of T cells, B cells anddendritic cells relative to adults, by an IFN production which is lowcompared to adults and by the fact that the secondary lymphoid organsare not fully mature. More specifically a “neonatal” or “newborn” in thecontext of the present invention may be defined as an infant animalhaving a number of splenic CD4+cells being preferably at least 2-fold,more preferably at least 20-fold, more preferably at least 200 fold,more preferably at least 2,000 fold, most preferably at least 20,000fold lower than the average number of splenic CD4+cells in adults.

In mice the immune system is mature at the age of 4 weeks. In humansmaturity is probably 6 month to 1 year. In cats and dogs the immunesystem is mature usually at the age of 6 month, in calves, sheep andpigs at the age of 4-12 weeks. The vaccination with the virus accordingto the present invention, in particular with MVA is preferably doneduring before the immune system is mature. However, since maturitydevelops almost exponentially after birth it is most preferred tovaccinate with the virus according to the present invention, inparticular with MVA as early after birth as possible. Since in allrelevant domestic animals and in humans the immune system is mature notearlier than 4 weeks after birth, it is generally preferable thatvaccination with the virus according to the present invention, inparticular with MVA, is done preferably within 4 weeks after birth, morepreferably within 2 weeks after birth, even more preferably within 1week after birth, most preferably within 3 days after birth. Thesegeneral terms are applicable to all important domestic animals, inparticular to all important domestic mammalian animals, includinghumans. The person skilled in the art will be aware of the fact thateven older animals may be regarded as newborns/neonatals in the contextof the present invention and that, thus, the vaccination may also besuccessfully carried out with older animals, when the immune system isnot yet mature 4 weeks after birth. Thus, in humans the vaccination maybe carried out within 6 month after birth, more preferably within 3month after birth, more preferably within 2 month after birth, morepreferably within 4 weeks after birth, more preferably within 2 weeksafter birth, even more preferably within 1 week after birth, mostpreferably within 3 days after birth.

Since the best effects of the virus according to the present invention,in particular MVA as a general vaccine are observed if the virus isadministered to an immature immune system, it might be preferred tovaccinate even prenatal animals including humans. Prenatal vaccinationmay be desirable in economically important animals such as cattle orpigs. If the placenta lets through the virus the prenate can bevaccinated simply by vaccinating the mother animal. Thus, thevaccination of the mother animal to vaccinate the prenate isparticularly promising in an animal having a placentaendotheliochorialis, such as dogs, cats, rats and mice or having aplacenta heamochorialis, such as primates including humans. In animalshaving a placenta chorionepithelialis, such as cattle and sheep orhaving a placenta syndesmochorialis, such as pigs and horses, thevaccination of prenates can be preferably done by in uteroadministration. Of course, this mode of administration can be also donefor animal having a placenta endotheliochorialis or haemochorialis.

Since the viruses according to the present invention, in particular MVAlead to an accelerated maturation of the immune system and since theviruses according to the present invention, in particular MVA are thususeful as a general vaccine, the vaccinated animals are protectedagainst a variety of diseases. More specifically the viruses accordingto the present invention, in particular MVA can be used to vaccinatecats for general well being and against feline herpes or felineinfectious peritonitis. The viruses according to the present invention,in particular MVA may be used in dogs for general well being and againstrespiratory tract associated (viral) diseases. The viruses according tothe present invention, in particular MVA may be used in pigs for generalwell being and against Hemophilus or Mycoplasm infections, especially infattening pigs.

As pointed out it is a preferred embodiment to use the viruses accordingto the present invention, in particular MVA, in newborns or prenatalanimals to protect said animal against a foreign antigen and/or a tumourantigen, wherein the tumour antigen is different from the antigensassociated with the virus used for vaccination. However this embodimentis not restricted to newborn and prenatal animals. Instead, in analternative embodiment the invention can be carried out for animals ofall ages, since a beneficial effect can be observed also in adultanimals. Thus, according to this embodiment the viruses as definedabove, in particular MVA-BN and its derivatives are useful to protect ananimal, including a human, against an antigen selected from tumourantigen and foreign antigen, wherein the tumour antigen and/or theforeign antigen is different from the antigens associated with thevirus. As pointed out above, the viruses used according to the presentinvention are capable of infecting cells of the animal but not capableof being replicated to infectious progeny virus in said cells. Allinformation, definitions, including the definition of the duration ofthe protective effect, examples as well as the preferred, more preferredand most preferred embodiments given above for neonates also apply forthe present embodiment according to which the virus may also beadministered to adults.

In contrast to newborns, the immune system of adult animals has alreadymatured. Nevertheless, it might be that the immune system is weakeneddue to certain diseases or simply due to the age of the animal.Especially in immune-compromised people and in elderly people theadministration of the viruses according to the present invention, inparticular MVA to the animal may have a beneficial effect inter alia byincreasing the level of factors activating and/or mobilizing dendriticcells (DC) or their precursor cells and/or by increasing the number ofdendritic cells or their precursor cells and/or by increasing theproduction and/or cellular content of an interferon or IL-12. Thus, evenin adult animals the administration of the viruses according to thepresent invention, in particular MVA may lead to an increased competenceof the immune system to deal with foreign antigens and/or tumourantigens. In other words, the viruses used according to the presentinvention are useful for the activation of the immune system in general.

The invention further concerns the viruses according to the presentinvention, in particular MVA for the preparation of a medicament to beadministered to an animal, including a human, wherein said medicamentincreases the level of factors which activate dendritic cells and/orincreases the number of dendritic cells and/or increases the productionand/or cellular content of an interferon (IFN) or IL-12. All definitionsgiven above for the other embodiments are also applicable for thepresent embodiment. According to this embodiment the invention does notaim primarily at inducing a protection against foreign antigens and/ortumour antigens. Instead, this embodiment is aimed at treatingconditions and diseases characterized by a low level of factors whichactivate dendritic cells and/or by a insufficient or too low number ofdendritic cells and/or by a low production and/or cellular content of aninterferon (IFN) or IL-12. Thus, according to this embodiment thetreatment with the viruses according to the present invention, inparticular MVA could protect against allergies or autoimmune diseases.Again this treatment is particularly promising if the viruses accordingto the present invention, in particular MVA are administered to newbornanimals.

Additionally, according to a further embodiment the virus according tothe present invention, such as MVA, in particular MVA-BN and itsderivatives, is particularly useful to induce immune responses inimmuno-compromised animals, e.g., monkeys (CD4<400/μl of blood) infectedwith SIV, or in immuno-compromised humans. The term “immuno-compromised”describes the status of the immune system of an individual, which showsonly incomplete immune responses or has a reduced efficiency in thedefence against infectious agents.

The invention further concerns a method for protecting an animal,including a human, against an antigen selected from tumour antigen andforeign antigen, by administration of a virus according to the presentinvention, in particular Modified Vaccinia virus Ankara (MVA), whereinthe tumour antigen and/or the foreign antigen is different from theantigens associated with the virus.

In a further embodiment the invention concerns a method for thetreatment of an animal, including a human, to increase the level offactors which activate dendritic cells and/or to increase the number ofdendritic cells and/or increase the production and/or cellular contentof an interferon (IFN) or IL-12, comprising the administration of aModified Vaccinia virus Ankara (MVA).

SUMMARY OF THE INVENTION

The invention inter alia comprises the following, alone or incombination:

An MVA virus characterized by

(i) being capable of reproductive replication in vitro in chicken embryofibroblasts (CEF) and by being non-replicative in vitro in human cells,and

(ii) by a failure to replicate in a mouse strain that is incapable ofproducing mature B and T cells and as such is severely immunecompromised and highly susceptible to a replicating virus, foradministration to induce a general immune stimulation in an animal,including a human, in need thereof, such a

MVA virus, wherein the human cells are the human keratinocyte cell lineHaCaT, the human embryo kidney cell line 293, the human boneosteosarcoma cell line (143 B), and the human cervix adenocarcinoma cellline HeLa, such a

MVA virus, which is MVA-BN deposited at the European Collection of CellCultures (ECACC), Salisbury (UK) under number V00083008 or derivativesthereof exhibiting the same replication characteristics, such a

MVA virus, wherein administration to the animal, including the human, inneed of general immune stimulation, increases (i) the level of factorswhich activate and/or mobilize dendritic cells or their precursor cells,(ii) the number of dendritic cells or their precursor cells, and/or(iii) the production and/or cellular content of an interferon (IFN) orIL-12, such a

MVA virus, wherein the general immune stimulation is characterized bystimulating a cell-mediated immune response, such a

MVA virus, wherein the general immune stimulation is characterized by anincrease in the number of dendritic cells and their precursor cells,such a

MVA virus, wherein the precursors of dendritic cells are plasmacytoiddendritic cell precursors, such a

MVA virus, wherein the general immune stimulation is characterized as anincrease in the number of T lymphocytes, such a

MVA virus, wherein the T lymphocytes comprise CD8+T cells and/or CD4+Thelper cells, such a

MVA virus, wherein the general immune stimulation is characterized by anat least 1.5 fold increase in the concentration of Flt3-L two days afteradministration of the virus, such a

MVA virus, wherein the animal, including the human, in need of generalimmune stimulation is receiving antiviral therapy, such a

MVA virus, wherein the antiviral therapy is for the treatment of a virusbelonging to the family Retroviridae, such a

MVA virus, wherein the virus belonging to the family Retroviridae isselected from HIV-1, HIV-2, SIV, Simian-Human immunodeficiency virus,Feline immunodeficiency virus, Bovine immunodeficiency virus and Equineimmunodeficiency virus, such a

MVA virus, wherein the antiviral therapy eliminates and/or suppresses aviral infection, such a

MVA virus, wherein the antiviral therapy includes administration ofnucleoside analogs, inhibitors of viral enzymatic activity, inhibitorsof viral assembly, cytokines and/or a combination thereof, such a

MVA virus, wherein the antiviral therapy is highly active antiretroviraltherapy (HAART), such a

MVA virus, wherein the animal in need of general immune stimulation is ahuman with an HIV-induced immune deficiency, such a

MVA virus, wherein the animal, including the human, in need of generalimmune stimulation, has a condition linked to low CD4+levels selectedfrom breast cancer, chronic lymphatic leukaemia (CLL), HIV infection,HIV infection with an opportunistic infection, Kaposi's sarcoma, andchemotherapy-induced lymphopenia, such a

method of inducing a general immune stimulation in an animal, includinga human, in need of general immune stimulation, comprising the step ofadministering to the animal, including the human, an effective amount ofthe MVA virus, such a

method wherein the MVA virus is administered by oral, nasal,intramuscular, intravenous, intraperitoneal, intradermal, intra-uteroand/or subcutaneous application, such a

method wherein the MVA virus is administered to the animal, includingthe human, in need of general immune stimulation in an amount of atleast 10¹ TCID₅₀ (tissue culture infectious dose), such a

method wherein administration to the animal, including the human, inneed of general immune stimulation, increases (i) the level of factorswhich activate and/or mobilize dendritic cells or their precursor cells,(ii) the number of dendritic cells or their precursor cells, and/or(iii) the production and/or cellular content of an interferon (IFN) orIL-12, such a

method wherein the general immune stimulation is characterized bystimulating a cell-mediated immune response, such a

method wherein the general immune stimulation is characterized by anincrease in the number of dendritic cells and their precursor cells,such a

method wherein the precursors of dendritic cells are plasmacytoiddendritic cell precursors, such a

method wherein the general immune stimulation is characterized by an atleast 1.5 fold increase in the concentration of Flt3-L two days afteradministration of the virus, such a

method wherein the general immune stimulation is characterized as anincrease in the number of T lymphocytes, such a

method wherein the T lymphocytes comprise CD8+T cells and/or CD4+Thelper cells, such a

method wherein the animal, including the human, is receiving antiviraltherapy, such a

method wherein the antiviral therapy is for the treatment of a virusbelonging to the family Retroviridae, such a

method wherein the virus belonging to the family Retroviridae isselected from HIV-1, HIV-2, SIV, Simian-Human immunodeficiency virus,Feline immunodeficiency virus, Bovine immunodeficiency virus and Equineimmunodeficiency virus, such a

method wherein the antiviral therapy eliminates and/or suppresses aviral infection, such a

method wherein the antiviral therapy includes administration ofnucleoside analogs, inhibitors of viral enzymatic activity, inhibitorsof viral assembly, cytokines, and/or a combination thereof, such a

method wherein the antiviral therapy is highly active antiretroviraltherapy (HAART), such a

method wherein the animal in need of general immune stimulation is ahuman with an HIV-induced immune deficiency, such a

method wherein the animal, including the human, in need of generalimmune stimulation, has a condition linked to low CD4+levels selectedfrom breast cancer, chronic lymphatic leukaemia (CLL), HIV infection,HIV infection with an opportunistic infection, Kaposi's sarcoma, andchemotherapy-induced lymphopenia, such a

method of inducing a general immune stimulation in an animal, includinga human, in need of general immune stimulation, comprising the step ofadministering to the animal, including the human, an effective amount ofan MVA strain, wherein the general immune stimulation is characterizedas an increase in the number of T lymphocytes, such a

wherein the MVA strain is selected from MVA-575 (ECACC V00120707),MVA-572 (ECACC V94012707) and the MVA virus, such a

method wherein the T lymphocytes comprise CD8+T cells and/or CD4+Thelper cells, such a

method wherein the animal, including the human, is receiving antiviraltherapy, such a

method wherein the antiviral therapy is for the treatment of a virusbelonging to the family Retroviridae, such a

method wherein the virus belonging to the family Retroviridae isselected from HIV-1, HIV-2, SIV, Simian-Human immunodeficiency virus,Feline immunodeficiency virus, Bovine immunodeficiency virus and Equineimmunodeficiency virus, such a

method wherein the antiviral therapy eliminates and/or suppresses aviral infection, such a

method wherein the antiviral therapy includes administration ofnucleoside analogs, inhibitors of viral enzymatic activity, inhibitorsof viral assembly, cytokines, and/or a combination thereof, such a

method wherein the antiviral therapy is highly active antiretroviraltherapy (HAART), such a

method wherein the animal in need of general immune stimulation is ahuman with an HIV-induced immune deficiency, such a

method wherein the animal, including the human, in need of generalimmune stimulation, has a condition linked to low CD4+levels selectedfrom breast cancer, chronic lymphatic leukaemia (CLL), HIV infection,HIV infection with an opportunistic infection, Kaposi's sarcoma, andchemotherapy-induced lymphopenia.

SHORT DESCRIPTION OF THE FIGURES

FIG. 1A: Newborn mice were injected once within 24-48 h of birth with10⁶ p.f.u. of MVA or DISC HSV-1 or treated with physiological saline(NaCl) as controls. At 7 days of age, CD11c, a pan DC marker was used todetermine these cells in peripheral blood by flow cytometry. Mean andstandard deviation of 3 to 5 experiments are shown.

FIG. 1B: Experiment as in FIG. 1A. However, CD11c cells were determinedin spleen by flow cytometry

FIG. 1C: Experiment as in FIG. 1A. However, CD11c cells were determinedin peritoneal fluid by flow cytometry

FIG. 2: Mice were vaccinated with MVA-BN as indicated in the leftcolumn. After two weeks the percentage of CD11c⁺single andCD11c⁺/CD8⁺double positive cells in spleen and in blood were determinedby flow cytometry.

FIG. 3: Newborn mice were injected with MVA or NaCl as control at dayone and 5 of age. At day 8, murine Flt3-L was determined in serum ofthese mice by ELISA and the values are given as pg/ml.

FIG. 4: Newborn mice were injected once within 24-48 h of birth with 106p.f.u. of MVA or treated with NaCl as controls. At 7 days of age, allmice were exposed to 100×LD₅₀ of HSV-1 strain F. The number of survivinganimals was monitored for 21 days.

FIG. 5: Mice were treated as in FIG. 4. The data represent 9 differentchallenge experiments with 100 LD₅₀ of HSV-1. None of the controlanimals survived the challenge.

FIG. 6: Survival of adult mice vaccinated on the first day of life withMVA-BN following a lethal vaccinia challenge. Three litters of 61-day-old pups (18 mice) were vaccinated with MVA-BN (2.5 ×10⁷ TCID₅₀)and at 4 weeks (adult mice) challenged with a lethal dose of vaccinia.MVA-BN vaccination clearly induced a protective immunity in neonatalmice that lasted until adulthood.

EXAMPLES

The following examples will further illustrate the present invention. Itwill be well understood by a person skilled in the art that the providedexamples in no way may be interpreted in a way that limits theapplicability of the technology provided by the present invention tothis examples.

EXAMPLE 1 (I) MVA-BN and DISC-HSV induces DC of the CD11c⁺andCD8⁺phenotype in newborn animals

First set of experiments: Newborn mice are naturally immunodeficientbecause the IFN system is not mature. The number and activation state ofDC, the best producers of IFN know today has not been analyzed. DC canbe induced in vitro as well as in vivo by a variety of stimuli. In thesestudies it was tested whether a controlled MVA-BN replication couldinduce DC and analyzed their phenotype. Groups of mice were injectedwith 10⁶ plaque forming units (p.f.u.) of MVA-BN or saline only within1-2 days after birth and in some cases 5 days after birth. Blood andspleen cells from individual mice of both groups were analyzed by FACSand the data compared.

Data from 7 to 8 individual mice indicated that treatment with MVA-BNincreased CD11c⁺cells 2-3 fold accompanied with increased expression ofMHC II and increased presence of T cells of the CD4 or CD8 typeInterestingly, CD19/54, a marker for mature B cells decreased indicatingthat these cells emigrated in organs other than spleen or that precursorof B cells were recruited early to other lineages notably DC of theplasmacytoid phenotype that carries early B cell markers (B220).

Data from three different experiments indicated reproducibility andsignificant differences. Experiments with DISC-HSV-1, a differentreplication controlled viral vaccine, induces similar amounts ofCD11c+cells after neonatal priming.

The results are summarized in FIG. 1A-C.

To further investigate subpopulations of DC in blood and spleen andanalyze long-term effect of treatment with MVA-BN, cells in blood andspleen were analyzed at 2 weeks of age. At this time point, treatedanimals had about twice the number of CD11c⁺cells in spleen than at oneweek of age but a single treatment with the virus at birth lead to a 3fold elevated number of these cells in spleen 2 weeks later (FIG. 2).Similar effects were seen in blood with the exception thatCD11c⁺/CD8a⁺were about 4 times higher. A single treatment with MVA-BN at7 days of birth lead to an increase of CD11c⁺/CD8a⁺from 13 to 40 foldwith a less dramatic effect on the CD11c⁺cells. As expected, twovaccinations at birth and day 7 had a significant effect on CD11c⁺cells.The various effects are shown in FIG. 2.

Second set of experiments: One-week-old mice that were vaccinated atbirth with 2.5×10⁷ TCID₅₀ of MVA-BN showed a different composition ofimmunologically relevant cell populations in spleen and blood thancontrol mice (Table 1). In blood there was an increase in the CD8positive lymphocyte population as well as an increase in the number ofNK cells. The number of CD11c positive cells was about 3 times higherthan in controls and the percent of B-cells (B220 and CD19 doublepositive cells) was significantly decreased. In the spleen the totalnumber of cells did not differ between immunised animals and controls.In contrast to the blood, the spleen of vaccinated animals had more CD4positive T lymphocytes than controls and the number of NK cells was notincreased. Similar to blood the relative number of CD8 positivelymphocytes were increased and the number of B-cells decreased. Thepercentage of CD11c positive cells was about 3 times higher than incontrols. We first recognised a difference in the percentage ofdendritic cells at day 5 following vaccination with MVA-BN, when thenumber of CD11c positive cells in the spleen of 4 untreated controlswere 3.6 %, compared to 4.8% in 4 MVA-BN vaccinated mice. The sameamount of UV-inactivated MVA-BN did not cause any significant change inthe cell populations after vaccination of neonatal mice compared tocontrols (data not shown). The initial vaccination dose was chosenarbitrarily. After titration of the inoculum we selected a standard doseof 2.5×10⁶ TCID₅₀ for vaccination (10 time less than in the initialexperiment). At this dose maximal numbers of DC were induced (Table 2).TABLE 1 Changes induced in blood and spleen cells in newborn mice 1 weekafter immunisation with 2.5 × 10⁷ TCID₅₀ MVA-BN Blood Spleen Parameter %NaCl MVA-BN P* NaCl MVA-BN P* Total cells × 10⁶ 17.9 ± 1.9  24.1 ± 2.6 0.105 % CD11c  5.4 ± 1.3 18.6 ± 1.5 0.001 2.8 ± 0.1 7.9 ± 0.8 0.001 %CD11c/CD8α  0.5 ± 0.1  2.7 ± 0.3 0.001 1.1 ± 0.1 4.6 ± 0.7 0.002 %CD4/CD3 16.9 ± 1.1 16.1 ± 1.5 0.999 4.8 ± 0.3 8.1 ± 1.5 0.004 % CD8α/CD3 6.0 ± 0.9 10.3 ± 0.9 0.002 4.7 ± 0.3 8.4 ± 1.1 0.002 % NK1.1/DX5 16.4 ±1.2 24.4 ± 3.3 0.032 2.5 ± 0.3 2.4 ± 0.2 0.862 % CD19/B220 22.3 ± 0.5 8.4 ± 0.8 0.001 16.2 ± 1.3  8.6 ± 0.9 0.004*Mann-Whitney U-Test

TABLE 2 Induction of CD11c positive cells in the spleen of 1-ay-old wtmice and mice with gene-targeted disruptions within 7 days afterMVA-treatment. Mouse MVA dose controls MVA-BN strain (TCID₅₀) % CD11c %CD11c ratio wt^(a) 2.5 × 10⁷ 2.8 7.9 2.8 wt 2.5 × 10⁶ 2.1 11.9 5.6 wt2.5 × 10⁵ 2.5 6.6 2.6 RAG^(b) 2.5 × 10⁷ 4.2 5.4 1.3 AG129^(c) 2.5 × 10³2.6 2.7 1.0^(a)Wt = either C57BL/6 or 129 Sv/Ev mice.^(b)RAG mice deletion in recombination activating gene (i.e nofunctional T and B cells).^(c)AG129 gene targeted disruptions of IFN receptor Type I (IFN-α and-β) and Type II (IFN-γ)

(ii) MVA-BN induces preferentially plasmacytoid dendritic cells (pDC).

According to other authors CD1 1c positive cells that also expressedCD45RA or CD45R were considered as pDC (Asselin-Paturel, et al. 2001,Nat Immunol, 12: 1144). It was asked whether MVA-BN induced an increaseof pDC. A further experiment was performed in which also CD45RA or CD45Ron CD11 c positive were analysed. The percentage of CD11c and CD45Rdouble positive cells was significantly higher in MVA-BN treated mice(5.6±0.7%) than in both control groups (untreated 3.0±0.3%, p=0.01;UV-inactivated MVA-BN 3.0±0.2%, p=0.006. Mann-Whitney U-test).

(iii) Neonatal mice treated with MVA-BN have elevated levels of serumFlt3-L

Flt3-L is a hematopoetic factor that leads to increased levels of DC inadult animals. In human and possibly mice the richest source of thisfactor are activated T cells. To determine whether the elevated numbersof DC could be the results of induced Flt3-L, serum of MVA-BN treatedmice was compared to mock treated animals for the presence of thisfactor. Animals treated at day 2 and 5 had twice the levels of Flt3-L inthe serum when compared to serum of mock treated animals. Hence, Flt3-Lis one of the factors that could be made responsible for elevatednumbers of DC (FIG. 3)

The time course of the Flt3-L induction in newborn mice was assessedafter administration of MVA-BN. In newborns, MVA-BN vaccination inducedan increase in Flt3-L concentration within 24 hours. The inductionreached a maximum after 48 hours and was still present at day 7, thetime when spleen cells were usually analyzed and resistance againstHSV-1 was tested (see below). In the vaccinated mice the Flt3-Lconcentration in the serum was two-fold increased 24 hours and 48 hoursafter the vaccination, compared with age matched control animals.

EXAMPLE 2

(i) MVA-BN treated neonatal mice survive a challenge with 100 to 500LD50 of HSV-1

Groups of mice were treated with the standard dose of MVA-BN one or 2days after birth and challenged at 7-8 days of age with 100 to 500 LD₅₀of Herpes simplex virus 1 (HSV-1) (FIG. 4). MVA BN treated mice survivedthe challenge with HSV 1, whereas all the control mice died within 5-6days after inoculating the challenge virus.

To further support these observations, 9 challenge experiments wereperformed with 40 MVA BN treated and 45 control mice. More than 80 % ofthe virus treated mice survived the challenge, whereas all the controlmice died (FIG. 5).

In a separate set of experiments the mice were treated at birth withMVA-BN (2.5×10⁶ TCID₅₀ mouse). At day 8 a challenge with either 10³ (1LD₅₀) or 10⁵ (100 LD₅₀) PFU of HSV-1 was performed. Following MVA-BNvaccination 65% of the mice survived a viral dose that killed 100% ofthe control mice (100 LD₅₀) and 90% survived a dose that killed 45.5% ofthe controls (1 LD₅₀). In additional experiments a group of 7 micevaccinated with UV-inactivated MVA-BN were infected with HSV-1. Five ofthem died within 7 days. The remaining 2 animals ceased to grow and diedat day 22 and 29. Therefore, mice treated with MVA-BN reached a state ofincreased resistance against HSV-1 that was associated with live MVA-BN,but not inactivated MVA-BN.

In control experiments done with mice that do not have functionalT-cells it was determined that the protection against HSV-1 aftervaccination with MVA-BN was not due to cross-reacting cytotoxic T-lymphocytes induced by MVA-BN.

It was tested whether DC cells were responsible for the protection ofmice from HSV-1 after vaccination with MVA-BN. To this end naive8-day-old mice were challenged with 5×10⁴ PFU HSV-1 4 hr after transferof cells from MVA-treated mice. In a first experiment splenocytes from8-days-old mice treated at 1 day of life with MVA-BN were separated inDC rich (low-density) and DC poor (high-density) fractions. Micereceiving 5×10⁶ cells from the DC rich fraction survived the challengeto 50% whereas all the mice receiving 10 times less DC rich suspensionor untreated mice died within 5 days. A second approach was done bytransferring positively isolated CD11c positive cells from 8-days-oldmice treated at 1 day of life with MVA-BN to naïve age matched mice. Asuspension of 2 ×106 splenocytes containing more than 80% CD11c positivecells from MVA-BN treated mice protected naïve mice from HSV-1infection. In contrast, 4 untreated littermates as well as 8 additionaluntreated animals died after the challenge. Furthermore, mice receivingthe same amount of spleen cells or mice receiving one spleen equivalent(50 ×10⁶ cells) from the negative fraction did not show increasedresistance against HSV-1. Thus CD11 c positive cells are able to protectmice from HSV-1.

After administration of MVA short-term protective effects in the rangeof about 24 hours were described in the prior art (Vilsmeier, B., Berl.Munch. Tierärztl. Wschr. 112 (1999), 329-333). Although the viruses usedin said publication are not viruses that are not capable of beingreplicated to infectious progeny virus in the neonatal or prenatalanimal used, it was tested whether the mode of action as disclosed inVilsmeier is similar to the mode of action described in the presentapplication. More particularly, Vilsmeier discloses that MVA, inparticular inactivated MVA, induces a paramunity for about 24 hours. Totest whether the paramunity effect counts also for the protectiveeffects as disclosed in the present application mice 24 hours of birthwere vaccinated either with MVA-BN or with inactivated MVA-BN. At 7 daysof age the mice were challenged with a lethal dose of HSV-1 (10 ⁵PFUHSF-1f). Unvaccinated control mice died 6 days after challenge. Also themice vaccinated with inactivated MVA-BN were not protected against achallenge with HSV-1. The number of DC cells in these mice was notelevated. In contrast, the mice vaccinated with non-inactivated MVA-BNwere significantly protected against a challenge with HSV-1. 30 daysafter the challenge more than 80% of the mice were still alive. Two daysafter vaccination elevated serum Flt3-L was found in the serum. Elevatednumbers of DC were found in the spleen. The enhanced Flt3-L wasassociated with elevated numbers of DC. This confirms that paramunityeffects are not responsible for the observed protection.

(ii) MVA-BN induces a specific immunity in neonates that lasts untiladulthood

One-day-old C57BI/6 mice (group size of 18) were vaccinated (i.p) withMVA-BN (2.5×10⁷ TCID₅₀). Four weeks after vaccination, when the micewere considered adults there where challenged with a lethal dose (1×10⁴TCID₅₀) of vaccinia Western Reserve (VV-WR). With the exception of oneanimal all other MVA-BN vaccinated animals survived. In contrast, allplacebo vaccinated animals died within 7 days and demonstrated severeclinical symptoms such as ruffled fur, weight loss and reduced activity.Clearly this is a clear demonstration that MVA-BN vaccination is notonly safe in neonatal animals, but is capable of inducing a protectiveimmune response against a lethal vaccinia (related virus to MVA-BN)infection.

1. An MVA virus characterized by (i) being capable of reproductivereplication in vitro in chicken embryo fibroblasts (CEF) and by beingnon-replicative in vitro in human cells, and (ii) by a failure toreplicate in a mouse strain that is incapable of producing mature B andT cells and as such is severely immune compromised and highlysusceptible to a replicating virus, for administration to induce ageneral immune stimulation in an animal, including a human, in needthereof.
 2. The MVA virus of claim 1, wherein the human cells are thehuman keratinocyte cell line HaCaT, the human embryo kidney cell line293, the human bone osteosarcoma cell line (143 B), and the human cervixadenocarcinoma cell line HeLa.
 3. The MVA virus of claim 1, which isMVA-BN deposited at the European Collection of Cell Cultures (ECACC),Salisbury (UK) under number V00083008 or derivatives thereof exhibitingthe same replication characteristics.
 4. The MVA virus of claim 1,wherein administration to the animal, including the human, in need ofgeneral immune stimulation, increases (i) the level of factors whichactivate and/or mobilize dendritic cells or their precursor cells, (ii)the number of dendritic cells or their precursor cells, and/or (iii) theproduction and/or cellular content of an interferon (IFN) or IL-12. 5.The MVA virus of claim 1, wherein the general immune stimulation ischaracterized by stimulating a cell-mediated immune response.
 6. The MVAvirus of claim 1, wherein the general immune stimulation ischaracterized by an increase in the number of dendritic cells and theirprecursor cells.
 7. The MVA virus of claim 6, wherein the precursors ofdendritic cells are plasmacytoid dendritic cell precursors.
 8. The MVAvirus of claim 1, wherein the general immune stimulation ischaracterized as an increase in the number of T lymphocytes.
 9. The MVAvirus of claim 8, wherein the T lymphocytes comprise CD8+T cells and/orCD4+T helper cells.
 10. The MVA virus of claim 1, wherein the generalimmune stimulation is characterized by an at least 1.5 fold increase inthe concentration of Flt3-L two days after administration of the virus.11. The MVA virus of claim 1, wherein the animal, including the human,in need of general immune stimulation is receiving antiviral therapy.12. The MVA virus of claim 11, wherein the antiviral therapy is for thetreatment of a virus belonging to the family Retroviridae.
 13. The MVAvirus of claim 12, wherein the virus belonging to the familyRetroviridae is selected from HIV-1, HIV-2, SIV, Simian-Humanimmunodeficiency virus, Feline immunodeficiency virus, Bovineimmunodeficiency virus and Equine immunodeficiency virus.
 14. The MVAvirus of claim 11, wherein the antiviral therapy eliminates and/orsuppresses a viral infection.
 15. The MVA virus of claim 11, wherein theantiviral therapy includes administration of nucleoside analogs,inhibitors of viral enzymatic activity, inhibitors of viral assembly,cytokines and/or a combination thereof.
 16. The MVA virus of claim 12,wherein the antiviral therapy is highly active antiretroviral therapy(HAART).
 17. The MVA virus of claim 1, wherein the animal in need ofgeneral immune stimulation is a human with an HIV-induced immunedeficiency.
 18. The MVA virus of claim 1, wherein the animal, includingthe human, in need of general immune stimulation, has a condition linkedto low CD4+levels selected from breast cancer, chronic lymphaticleukaemia (CLL), HIV infection, HIV infection with an opportunisticinfection, Kaposi's sarcoma, and chemotherapy-induced lymphopenia.
 19. Amethod of inducing a general immune stimulation in an animal, includinga human, in need of general immune stimulation, comprising the step ofadministering to the animal, including the human, an effective amount ofthe MVA virus of claim
 1. 20. The method of claim 19, wherein the MVAvirus is administered by oral, nasal, intramuscular, intravenous,intraperitoneal, intradermal, intra-utero and/or subcutaneousapplication.
 21. The method of claim 19, wherein the MVA virus isadministered to the animal, including the human, in need of generalimmune stimulation in an amount of at least 1 01 TCID₅₀ (tissue cultureinfectious dose).
 22. The method of claim 19, wherein administration tothe animal, including the human, in need of general immune stimulation,increases (i) the level of factors which activate and/or mobilizedendritic cells or their precursor cells, (ii) the number of dendriticcells or their precursor cells, and/or (iii) the production and/orcellular content of an interferon (IFN) or IL-12.
 23. The method ofclaim 19, wherein the general immune stimulation is characterized bystimulating a cell-mediated immune response.
 24. The method of claim 19,wherein the general immune stimulation is characterized by an increasein the number of dendritic cells and their precursor cells.
 25. Themethod of claim 24, wherein the precursors of dendritic cells areplasmacytoid dendritic cell precursors.
 26. The method of claim 19,wherein the general immune stimulation is characterized by an at least1.5 fold increase in the concentration of Flt3-L two days afteradministration of the virus.
 27. The method of claim 19, wherein thegeneral immune stimulation is characterized as an increase in the numberof T lymphocytes.
 28. The method of claim 27, wherein the T lymphocytescomprise CD8+T cells and/or CD4+T helper cells
 29. The method of claim19, wherein the animal, including the human, is receiving antiviraltherapy.
 30. The method of claim 29, wherein the antiviral therapy isfor the treatment of a virus belonging to the family Retroviridae. 31.The method of claim 30, wherein the virus belonging to the familyRetroviridae is selected from HIV-1, HIV-2, SIV, Simian-Humanimmunodeficiency virus, Feline immunodeficiency virus, Bovineimmunodeficiency virus and Equine immunodeficiency virus.
 32. The methodof claim 29, wherein the antiviral therapy eliminates and/or suppressesa viral infection.
 33. The method of claim 29, wherein the antiviraltherapy includes administration of nucleoside analogs, inhibitors ofviral enzymatic activity, inhibitors of viral assembly, cytokines,and/or a combination thereof.
 34. The method of claim 30, wherein theantiviral therapy is highly active antiretroviral therapy (HAART). 35.The method of claim 19, wherein the animal in need of general immunestimulation is a human with an HIV-induced immune deficiency.
 36. Themethod of claim 19, wherein the animal, including the human, in need ofgeneral immune stimulation, has a condition linked to low CD4+levelsselected from breast cancer, chronic lymphatic leukaemia (CLL), HIVinfection, HIV infection with an opportunistic infection, Kaposi'ssarcoma, and chemotherapy-induced lymphopenia.
 37. A method of inducinga general immune stimulation in an animal, including a human, in need ofgeneral immune stimulation, comprising the step of administering to theanimal, including the human, an effective amount of an MVA strain,wherein the general immune stimulation is characterized as an increasein the number of T lymphocytes.
 38. The method of claim 37, wherein theMVA strain is selected from MVA-575 (ECACC V00120707), MVA-572 (ECACCV94012707) and the MVA virus of claim
 1. 39. The method of claim 37,wherein the T lymphocytes comprise CD8+T cells and/or CD4+T helpercells.
 40. The method of claim 37, wherein the animal, including thehuman, is receiving antiviral therapy.
 41. The method of claim 40,wherein the antiviral therapy is for the treatment of a virus belongingto the family Retroviridae.
 42. The method of claim 41, wherein thevirus belonging to the family Retroviridae is selected from HIV-1,HIV-2, SIV, Simian-Human immunodeficiency virus, Feline immunodeficiencyvirus, Bovine immunodeficiency virus and Equine immunodeficiency virus.43. The method of claim 40, wherein the antiviral therapy eliminatesand/or suppresses a viral infection.
 44. The method of claim 40, whereinthe antiviral therapy includes administration of nucleoside analogs,inhibitors of viral enzymatic activity, inhibitors of viral assembly,cytokines, and/or a combination thereof.
 45. The method of claim 41,wherein the antiviral therapy is highly active antiretroviral therapy(HAART).
 46. The method of claim 37, wherein the animal in need ofgeneral immune stimulation is a human with an HIV-induced immunedeficiency.
 47. The method of claim 37, wherein the animal, includingthe human, in need of general immune stimulation, has a condition linkedto low CD4+levels selected from breast cancer, chronic lymphaticleukaemia (CLL), HIV infection, HIV infection with an opportunisticinfection, Kaposi's sarcoma, and chemotherapy-induced lymphopenia.